最新刊期
卷 ， 期 2 ， 2006
- 摘要：The effects of smelting and crystallization condition on microstructure and mechanical properties of AZ91D were investigated.The results show that the holding time of melt has little effects on the microstructure of re-melting samples in permanent mold.The grain size of the alloy is firstly decreased and then increased with the increase of the holding time,resulting in the earlier increase and then decease of tensile strength and elongation of the alloy samples.The crystallization condition can affect solidification ways of the alloy.The microstructure of the AZ91D alloy is composed of the matrix phase and γ phase under the condition of equilibrium solidification while the divorced eutectic structure occurs in microstructure under the condition of the non-equilibrium solidification.关键词：Cooling Rate;Holding Time;AZ91D Magnesium Alloy;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：The microstructure of mullite/Al-Cu-Si composites prepared by squeezing casting was observed by ATEM.The results indicate that the mullite fibre is composed of fine grains with different size and orientation as well as uneven distribution.High density dislocation presents in quenched fibre/matrix interface and in Si phase/matrix interface near to the matrix.Interface compounds in interface of mullite/Al-Cu-Si are not found,while the non-equilibrium θ（Al2Cu） phase is precipitated in fibre/matrix interface with a higher Si content.关键词：Mullite Fibre;Al Matrix Composites;Interface Microstructure;Interface Constituent
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发布时间：2023-12-18 -
- 摘要：Si-Ca-Ba alloys have much stronger ability in deoxidation and inclusion modification.Si-Ca alloy and Si-Ca-Ba alloy as deoxidizers and nonmetallic inclusion modifications used for soft magnetic 1JHA1 alloy in AIM （air induction melting ） are investigated.It is found that gas content in trial alloy can be reduced and nonmetallic inclusion can be significantly decreased to below 0.5 grade by using Si-Ca-Ba alloys as final deoxidizer compared with Si-Ca alloy,meanwhile,spheroidized residual inclusions are more uniformly distributed in the alloy,and the alloy possesses higher magnetic properties and more uniform microstructure.关键词：Soft Magnetic Alloys;Si-Ca-Ba Alloy;Nonmetallic Inclusion Modification
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发布时间：2023-12-18 - 摘要：The effects of different Zr contents on the grain size and as-cast mechanical properties of the MgZn5Nd3.5 alloy were studied.Microstructural observation indicates that grain size is increased with increase in the Zr content in case of Zr content less than 0.8%,while the grain size is somewhat changed with that in case of Zr content more than 0.8%.From the mechanical property measurements indicate that Zr addition can improve as-cast tensile strength and elongation of the alloy.SEM analysis shows that alloy rupture changes from quasi-cleavage fracture to ductility fracture.关键词：Casting;Mg Alloy;Zr;Grain Refinement
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发布时间：2023-12-18 - 摘要：Abstract The grain growth and bending fatigue was examined for heat treated CuAlNi shape memory alloy with column crystal in heat mould continuous casting at four kinds of drawing velocity, such as 240mm/min, 360mm/min. 480mm/min. Precipitation of γ2 phase in CuAlNi shape memory alloy can be inhibited at drawing velocity more than 240mm/min, and increased to 480mm/min, the equiaxed crystal is formed in the alloy due to chilling effects acted on melt front during solidification. The critical drawing velocity during column crystal growth is observed at 360mm/min, and more than the velocity, the grain is sharply grown while less than the velocity, the grain size can be refined with increase in drawing velocity, where bending fatigue can be considerably improved by heat treatment eliminating the internal stress.关键词：Heat Mould Continuous Casting;CuAlNi Shape Memory Alloy;Grain Growth;Bending Fatigue
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发布时间：2023-12-18 - 摘要：A mathematical model for Ti molten filling in vertical centrifugal casting and its corresponding numerical modeling were established through analyzing acted forces,which was verified by hydraulic experiment.The simulated results are well in agreement with experimental ones.The theoretical analysis and experimental results reveal that filling volume is increased with raising filling time and centrifugal velocity,however,very high centrifugal velocity can result in the decrease of molten filling volume in cavity.关键词：Vertical Centrifugal Casting;Molten Ti Alloy;Filling;Numerical Simulation
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发布时间：2023-12-18 - 摘要：A new method for mold filling simulation based on body-fitted coordinate （BFC） is presented.Grid enmeshment,conversion and discretisation of governing equation and the treatment of free surface are discussed.Comparison between BFC and conventional mold filling simulation method is conducted by several simulation examples.The results show that in case of same grid density,BFC method can achieve higher precision.Moreover,BFC has the advantages in grid system,CPU time and memory consumption compared with the conventional method based on Cartesian orthogonal grid system.关键词：Mold Filling Simulation;BFC;Fluid
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发布时间：2023-12-18 - 摘要：The simulation of aluminum alloy in low frequency electromagnetic casting was performed by the ANSYS finite element method.In case of the frequency 15 Hz,current 150 A,coils 80,the magnetic flux intensity distribution in inter and outer of the ingot was analyzed,where the experiment was conducted also.The results show that the surface of the ingot is smooth,and its grain size is fine and globular,eliminating surface cold shut and exudations.The reason for the improved quality of the ingot is discussed.关键词：Electromagnetic Field;Casting;Numerical Simulation;Aluminum Alloy;Microstructure
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发布时间：2023-12-18 -
- 摘要：The distribution of residual stress in local Fe particle concentration region of Cu-Fe-P alloy for lead frame was simulated by a kinetic model based on the asto-plastics deformation finite element method,and the effects of Fe particles density on the residual stress of the materials were stressed.The results show that the residual stress of Cu matrix and Fe article near interface is increased with the increase of the Fe particle density.Meanwhile,Fe particle is compressed and Cu matrix is extended in the X direction while the Fe particle is extended and the Cu matrix is compressed in Y direction,which results in the increase of the stress difference between both sides of the interface,even leading to be torn of the interface and the advents of the surface peeling,influencing the properties of the Cu-Fe-P alloy.关键词：Fe Particle;Cu-Fe-P Alloy;Finite Element Method;Residual Stress
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发布时间：2023-12-18 - 摘要：The microstructure and mechanical properties of Al-20Cu alloy prepared by solid-liquid mixed casting were investigated by OP and SEM.The results show that grain size of α-Al phase in the alloy can be refined obviously,which is controlled less than 100 μm and spheroidized,and coarse dendrite can be eliminated.The eutectic lamellar spacing of CuAl2-Al（Cu） in the alloy is reduced.Compared with those of the alloy in conventional casting,the tensile strength and elongation of the alloy in liquid-solid mixed casting are increased from 112 MPa to 205 MPa,and from 0.5% to 3.5%,respectively.关键词：Casting;Solid-liquid Mixed Casting;Semi-solid Casting;Al-Cu Alloy
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发布时间：2023-12-18 - 摘要：The slurry stability time of semi-solid slurry prepared is one of the key factors of whether the semi-solid rheomolding can be industrialized.The effects of holding time on microstructure of semi-solid ZL117 alloy slurry are discussed.Experiment indicates that with extending holding time,although the solid volume fraction is little affected,average particle degree of primary Si in the slurry is obviously increased.Meanwhile,shape of primary Si becomes more and more sharp before 15 min,and shape is little changed due to the aggregation of the primary Si after 15 min.关键词：Hypereutectic Al-Si Alloy;Electromagnetic Stirring;Semi-solid;Primary Si;Holding Time
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发布时间：2023-12-18 - 摘要：Low volume fraction of short mullite fibers reinforced aluminum/silicon （M124F） alloys were prepared by the squeezing-casting process.The hardness,thermal expansion coefficient and the tensile strength of the composites were investigated from room temperature to 400 ℃.It is found that the tensile strength of the composites at room temperature is somewhat inferior to that of the M124F alloy.However,mullite fibers exert a beneficial effect on improving the tensile strength of M124F alloy at higher temperatures by more than 15% compared with other fibre reinforced composites.The fracture morphology of the composites specimens is observed with SEM to show the failure mechanism of the composite,where micro-crack is propagated in the interface between reinforced fibre and the matrix.关键词：Squeezing-casting Process;Mullite Fibers;Al Alloy Matrix Composites;Behaviors
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发布时间：2023-12-18 - 摘要：The Chinese die casting production volume reaches one million tons and its turnover is about thirty-five billions renminbi in 2004 year,involving in automobile,motocycle,machinery equipment,electric appliance and 3C parts.There presents about three thousands enterprises for die casting,in which about two hundreds of enterprises are more than one thousand tons in production volumes.About annual 4 500 die casting machines were manufacture,where turnover is near to three billions renminbi.The manufactured largest die castings are 30～40 tons for automobile and are 20～30 tons for elevator.The experience of enterprises with cost-efficiency involve in customer structure,product structure,cost-control and improvement of product-addition value as well as innovation.关键词：Die Casting;Production Volume;Product;Market
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发布时间：2023-12-18 - 摘要：The high cycle fatigue properties of AZ91D die cast magnesium alloy were investigated under the condition of stress ratio R=0.1.Fatigue strength of AZ91D magnesium alloy at ambient temperature is about 44% of tensile strength.Some defects in AZ91D Mg alloy,such as inclusion,can induce the formation of fatigue crack due to stress collection.Observation from AZ91D Mg alloy fracture morphology indicates that it is composed of fatigue source zone,fatigue crack propagation zone and fatigue fracture zone,where the fatigue lines is not evident and fatigue fracture morphology is quasi-cleavage fracture.关键词：Die Cast Magnesium Alloy;Stress Ratio;High Cycle Fatigue;Facture
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发布时间：2023-12-18 - 摘要：An equivalent hot spot design method for riser was designed through application of equivalent hot spot in riser design.The diameters of riser outlet,diameter of riser,riser volume and riser height for gating system can be calculated based on the table of simplified castings sectional area from equivalent riser diameter.The equivalent hot spot method for riser design has the advantages of direct visual and simple calculation.关键词：Investment Casting;Riser Design;Equivalent Hot Spot
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发布时间：2023-12-18 - 摘要：There easily exists shrinkage porosity due to superheat of ingate root in large plain parts investment casting.To argue the distance between mold end and castings,the wax pattern block was set.Actual production shows that if the wax pattern is set on wax mold end,the shrinkage is not eliminated,while in turn,wax pattern block is set on the castings,the shrinkage is eliminated.关键词：Investment Casting;Large Plain Castings;Ingate
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发布时间：2023-12-18 - 摘要：Technological measures for gating feeding system of valve castings in investment casting were given based on their structures and characteristics are used to reduce shrinkage porosity and shrinkage hole and to improve the quality of the valve castings.For the different structure and geometry condition of butterfly-valve,ball valve and brake valve,different design sketches of gating systems were proposed,and the practical way of empiric formula for gating system was given also.关键词：Hot Spot;Cooling Modulus;Investment Casting
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发布时间：2023-12-18 - 摘要：Aiming at the easy-oxidation and easy-ignition characteristics of elevated magnesium melt,a conveyer for elevated Mg alloy melt with melt back-brake mechanism was developed,in which gas-pressure delivery and fixed volume were used.The results from producing round plate show that the average standard error is 0.014 and average square error is 0.061 for delivery volume.The delivery precision reaches ±5%,effectively preventing the back-flow of the magnesium alloy melt.关键词：Magnesium Alloy;Conveyer;Structure Design;Precision
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发布时间：2023-12-18 - 摘要：Energy and electron structure of trace Sc,Zr,respectively,and mixed Sc,Zr adding into Al alloy based on the first-principle pseudopotential plane-wave method were investigated.The results show that the cohesive energies and generation heating of Al-Sc,Al-Mg-Sc,Al3Sc,Al-Zr,Al-Mg-Zr,Al3Zr,Al-Sc-Zr,Al-Mg-Sc-Zr are higher than those of pure Al and Al-Mg alloy,exhibiting the easy generation and structure stability of these crystal cells in Al-Mg system alloy.Through further analyzing the densities of states （DOS）of the crystal cell,it is found that there are more amounts of bonding electron numbers near the Feimi level of the alloy system with mixed Sc and Zr addition than those of ones with Sc or Zr addition,respectively.The refinement effects of mixed Sc and Zr addition are superior to those of Sc or Zr addition,respectively,which is contributed to more grain as the heterogeneous nucleation sites with mixed Sc and Zr addition during solidification process.关键词：Pseudopotential Plane-wave Method;Cohesive Energy;Generation Heating;Electron Density
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发布时间：2023-12-18 - 摘要：Under the condition of hand-molding with green clay sand,improvements in process for large thick-walled G-AlSi10Mg alloy frame castings was conducted to optimize the gating system.The experiment indicates that using bottom gating system with large orifice discharge in conjunction with installing cold iron and riser-head can realize the proportional solidification and then avoid shrinkage porosity （hole）,so that qualified frame castings is poured and the production rate is improved.关键词：Large Thick-walled Frame Castings;Processing Optimization;G-AlSIi0Mg Alloy;Proportional Solidification;Large Orifice Discharge
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发布时间：2023-12-18 - 摘要：The Cu-cladding Al rod composed of outer Cu and inner Al with outer-diameter of 40 mm,Cu wall thickness of 8 mm and length of 80 cm was prepared successfully by self-developed continuous casting machine with proper matches of processing variables.The solid-liquid interface,surface quality of Cu tube and mutual diffusion between Cu-Al interface are controlled by molten temperature,contacted length between water-cooling Cu sleeve and graphite lining,drawing velocity,position and flow rate of secondary cooling water.Compound rod with smooth surface and good cladding can be prepared by setting liquid-solid interface position at 5～10 mm away from crystallier outer-let,and Cu-cladding Al wire with different diameters after extrusion and drawing process can be produced.关键词：Continuous Casting;Cu-cladding Al Rod;Processing Variables;Solid-liquid Interface;Cu-cladding Al Wire
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发布时间：2023-12-18 - 摘要：The appearance of carbon fibre before-and -after preheatment and carbon fibre preforms was observed by SEM （scanning electron microscope）,and the distribution of the fibre in the carbon fibre reinforced ZL109 matrix composites prepared by squeezing casting was investigated by optical microscope.The results show that carbon fibre preheated can meet the requirements of preparation of qualified preform in length/diameter ratio,which assists in the uniform distribution of the fibre in the preform formed and formation of the preform.The fibre in the preform formed by squeezing casting is characterized by uniform distribution,non-aggregation on surface and oxidation free.The fibre is uniformly distributed in the ZL109 matrix of Cf/ZL109 composites prepared by squeezing casting,where the fibre possesses orientation.关键词：Squeezing Casting;Carbon Fibre;Carbon Short Fibre Preform;Carbon Fibre Reinforced Metal Matrix Composites
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发布时间：2023-12-18 - 摘要：The microstructure and wear resistance of TiC reinforced steel matrix surface composites prepared in Ti-C-Al-Ni system by SHS-casting method were investigated.The results show that the reinforced particle well bonded with the steel matrix in the steel matrix surface composites in the SHS-casting method.Uniform and round TiC particle with size 1～2 μm is distributed in the matrix,and the surface hardness with gradient distribution from the surface to the steel matrix is more than 950 Hv.The wear resistance of the composites is 5.6 times higher than that of the steel matrix,resulting in the dense fine round TiC particle with high hardness significantly decreasing the wear rate during wear process,showing excellent wear resistance.关键词：SHS-casting;TiC;Steel Matrix Surface Composites;">
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发布时间：2023-12-18
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